Percussive tool



May 5, 19%,

F-. D. BYERS PERCUSSIVE TOOL Original Filed April 29, 1935 Fig. 1. 23

1 Frederic/4 Do 5) 18 L i 18a rman Bye/"6 Patented May 5, 1936 UNITED STATES PATENT. OFFICE v PERCUSSIVE TOOL Original application April 29, 1935, Serial No.

18,921. Divided and this application November 6, 1935, Serial No. 48,592. In Great Britain May 5, 1934 9 Claims. (01.1255-42) This invention relates to percussive tools and is a division of my prior application SerialNo. 18,921, the said tools being of the kind in which the hammer comprises a reciprocating frame (hereinafter referred to as an oscillator) on which are mounted for rotation in opposite directions two or more rotary members (hereinafter referred to as fliers) driven by a bevel pinion I .splined to a motor shaft, and having their centres of gravity outside their centres of rotation and so disposed that at two points in a revolution the two centres of gravity and the axis of rotation are in the plane of the direction of movement of the oscillator. The invention more particularly relates to the kind of tool wherein the couple generated by the oscillatory gear is utilized for imparting rotary motion by means of a ratchet.

The object of the invention is to provide an improved form of such ratchet mechanism whereby excessivemovements of the hammer or oscillator .may .be checked, and stresses imposed on the mechanism by outside causes, such as the sticking of a drillsteel, may be reduced.

' According to the invention the ratchet mechanism is mounted so as to be free to rotate in the tool casing, and to be slidable against a resilient member which is housed in a member secured to the end of the tool casing.

The invention will now be described by way of example with reference to the accompanying drawing.

In the said drawing:-

Fig. 1 is a longitudinal sectional elevation of an electric pick or hammer drill comprising the mechanism according to the invention.

Fig. 2 is a sectional plan of Fig. 1.

Fig; 3 is a section taken on the line III-III of Fig. 2.

Fig. 4 is a section Fig. 1.

Fig.5 is a partial sectional elevation of an alternative form of ratchet mechanism for the tool holder. 7

Fig. 6 is a section taken on the line VIVI of Fig. 5.

Referring more particularly to the drawing, the numeral l indicates the motor casing, and 2 the motor shaft which has an extension 3 thereon projecting into an oscillator casing 4. Slidably mounted in the casing 4 is an oscillator in the taken on the line IV-IV of 7 available.

form of a closed yoke formed of a single piece of material, in which are rotatably mounted two similar coaxial and oppositely disposed bevel wheels or discs 6, l driven by a common bevel pinion 8 rigid with a splined sleeve 9 slidable on the motor shaft extension 3 which is correspondingly splined, the sleeve 9 being carried by a journal bearing I0 in a housing 5a in the inner cross member of the oscillator 5. The sleeve 9 has a shoulder 9a adapted to abut against the inner race of the bearing l0, while the outer race of the said bearing I0 is retained in the housing So by means of a steel retaining ring 20. By this means the pinion 8 is constrained against axial movement away from the discs 6, l.

The discs 6, l are rotatably mounted on a hollow spindle 2| which is similarly reduced at both ends, the one end passing into a correspondnally threaded retaining ring 22 adapted toscrew into a coaxial threaded bore in the other yoke arm. The spindle 2| can thus be inserted in posi tion without the necessity ofdividing theyoke.

Mounted on each of the bevel discs 6, l is a semi-circular weight ll, I2 respectively. It is desirable that the mass of the flyweights should be as great as possible, having regard to the space The end of the oscillator remote from the motor has formed thereon a splined nose 5b which-engages in a correspondingly splined socket in a tool holder l3. The tool holder I3 has mounted thereon pawls M which engage with ratchet teeth l5a. on a ratchet ring I5 which is housed in the end of the casing 4. The tool holder I3 is mounted to move outwards against a spring l6 housed in a cap 23 in threaded engagement with the outer end of the casing 4. The outer surface of the housing 5a forms a support and means of location for a recoil spring I1, which at its other end rests on a similar cylindrical support formed on the motor casing I. The projecting surfaces 5d are arranged to support the hammer 5 by revolving or sliding within the casing 4 as in a bearing.

The most effective shape is a halfhole in I5, the tool holder [3 having a shoulder |3a to prevent longitudinal movement through I5. The tool holder also carries an abutment washer 24 for the spring IS. The pressure of the spring [6 transmitted by the tool holder l3 to the ratchet ring I 5, holds the ring against .a shoulder 4a formed inside the casing 4. Should the hammer meet with little or no resistance during its forward movement, the faces 50 and .l.5b will come into contact, and the ratchet ring l5,

the tool holder I3, and the pawls l4 willajll travel with the hammer, until its energy is absorbedby the spring IS. The maximumtravelagainst the spring is limited by the shoulder 2311 on themside of the cap 23.

The ratchet is thus kept in full engagement,

the pawls and ring always occupying 'thesame positions relatively to each other, even during over-travel of the hammer. "The relative position of tool and tool holder are also unaltered. The friction between the ring [5 and the .casingaA which determinesthe torguewhich may be translmitte'd by the ratchet, is dependent upon the tinitialpres sure of the springf'l'fi and may thus .:be adjusted to avalue which will permit the ring ,30 to slip when the loadbecomes excessive.

The mechanism operatesas followsz- "When the motor is running, the discsB,'1 will be driven 'in Opposite directions, and in view of their centres of gravity not being at their centre .35 of rotation a centrifugal force will be set up by each disc along a line joining the centre of rotation and thecentres of gravity of the discs; and the following sequence will occur in a complete .revolution: V .4 When the centres of gravity of the discs 6, '1 are both in the plane of the centre "line of the "oscillator 5, 'the'centrifugal force or forces .will 'act inthesame direction and will carry the oscillator'5jinthatdirection. In the position shown ,;15 in the drawing-this movement will be to the left. After the discs16, 7 'have'turned'through a right angle-inoppositedirections, the centrifugal forces will actin opposite directions at rightangles to V the centreline of'the oscillator 5 so that there .50 will be no resulting force on the oscillator 5; but -owing to-thetW0 discs being in different planes, '"there willbe about the axis of the oscillator -5 'a -couple,--which will be referred to hereinafter. =When the discs 6, =1 have turnedthrough a-fur- .55 th'er right angle, their centres of gravity will again be in the plane of the axis of the oscillator 5, "but at 180 tothe previous position they occupied in this-'p1ane, so that centrifugalforces will again be set up along-the axis-of the oscillator .60 5 but in the opposite direction, with the result that-the oscillator-5will-be madeto travel in'the opposite direction. Whenthediscs-(i, 1 have movedthrough a third -right"angle the centrifugal forces are again act- .55 ing'in opposite directions at right "angles to the .centre-line of the oscillator and there will be no resultant movement; and again'therewill be a -oouple, but in a direction opposite to-that "menticned above. 7 1Z0 7 The movement'of the oscillator 5 along its axis "towards the motor end of the tool is absorbed -by the recoil spring l1, while its movement 'towards the tool end 'is'utilized to impart a series of impacts against the tool holder [3 or'agalnst 7-5 the tool itself. r

The couple referred to above may be utilized for imparting to the tool holder partial rotation about the axis of the oscillator, by mounting the oscillator for rotation about its axis in a holder, and arranging a ratchet mechanism between the 5 oscillator and the holder so that an intermittent rotary motion may be imparted to the tool or other holder.

In the construction shown in Fig. 1 the ratchet l5 being normally held ,rigid v.vviththe casing 4, 10V

and the tool holder [3 beingsplined with the oscillator 5, an intermittent rotation will be impart- .ed to the tool holder, the couple in the oscillator 5 in the opposite direction being taken up by the-casing of the tool. 15

In the construction shown in Figs. 5 and 6, the

ratchet ring "18a is made integral with the tool holder I 8 whilethe pawls M are mounted ona pawl carrier ,ISsWhich is splined with the oscillator nose 5b. Hence in the one direction of an- 20 ;gular oscillationof-the oscillator 5 the tool holder 18 is turned, while in the other direction the casing, a ratchet mechanism operated -by "said hammer, said ratchet mechanism .beingmounted in said casing so as to be free to rotate andtobe slidable therein, .a casing secured to the .endof the tool casing, and ,a resilient.memberinsaid'fl casing adapted .to abut against said ratchet mechanism.

.2. A percussive tool according to claim .1,

wherein the ratchet mechanism comprises .a

ratchet ring slidably andrevolubly mounted .in 40 the end of the tool casing.

3. A percussive tool according to claim 11...comprising a'hammer, a tool iholderin driving relation with the hammenpawls onsaidtool holder adapted'to engage with a ratchet .ring separate from saidtoolholder, saidratchet. ring being slidably .andrevolubly mounted initheendof the tool casing.

4. A percussive tool according to claimll .comprising a hammer. a tool'fholder.indrivingrelw tion with the hammer, pawls onsaid jtool holder adapted'fto engage with aratchetring'separate from said tool holder, said ,ratche't ring 'lbein'g slidably and revolubly mounted in the end. of the tool casing, a shoulder on said ratchet .r ne r adapted 'to abut against a corresponding, sihoulder in the tool casing, said resilient member abutting againstsaid ratchet ring.

5. A percussive tool according to claim 1 comprising ahammer, a tool holder in driving ,relamo tion with thehammer, pawls on said 'toolholder adapted .to engage witha ratchet ring separate from said tool holder, said ratchet ring slidablyandrevolubly mounted in the end .of-lthe tool casing, a shoulder on said ratchet ring ma 7 adapted to abut against a corresponding shoulder .in the-tool casing, said resilient member abutting against said ratchet-ring through an abutmerit ring.

7. A percussive tool according to claim 1 comprising a hammer, a tool holder, a. ratchet ring integral with said tool holder, a pawl holder in driving relation with said hammer and pawls on said pawl holder adapted to engage with said ratchet ring and a resilient member adapted to abut against said ratchet ring and tool holder.

8. A percussive tool according to claim 1 wherein a recess is formed between the resilient member housing and the ratchet mechanism to; allow of axial movement of said ratchet mechanism.

9. A percussive tool according to claim 1 5 wherein the resilient member housing is longitudinally adjustable relatively to the tool casing.

FREDERICK DORMAN BYERS. 

